HIV positive individuals can develop hearing difficulties, but the location of the problem (e.g. middle ear, cochlea, central nervous system (CNS)) and the relationship to treatment has not been known. Results from our ongoing NIDCD-funded study in Tanzania show that patients on anti-retroviral therapy (ART) have findings consistent with a central auditory processing disorder. This suggests that (a) hearing deficits in HIV-positive individuals could be another neurocognitive side effect of HIV infection, (b) certain ART regimens might produce central nervous system side effects that manifest themselves as hearing difficulties, (c) some ART regimens may treat CNS HIV inadequately, which is reflected as a central hearing deficit, and/or (d) monitoring of central hearing parameters could be a method to track central effects of either HIV or ART. These findings need to be confirmed, expanded, and related definitively to particular treatment regimens. The objective of the proposed study is to assess central auditory processing (e.g. gap detection thresholds, auditory brainstem response, speech-in-noise thresholds) in a large cohort of HIV positive individuals at the main AIDS treatment site in Shanghai China. The combination of this audiological testing protocol, with the population under treatment in Shanghai, will provide a powerful combination to answer questions about central processing disorders in patients with HIV and to relate the findings to particular drug regimens. Our study will use a laptop-based hearing testing system that includes: native-language questionnaire administration for self-reported hearing capability and exposure to noise, drugs and toxins; threshold audiometry; adaptive gap detection testing; speech-in-noise testing in Mandarin; tympanometry; and auditory brainstem response testing to assess brainstem pathways. Testing will take place at the Shanghai Public Health Clinical Center--the AIDS treatment center for Shanghai, China. The center follows 2000 AIDS patients, offers both outpatient and inpatient treatment, is affiliated with Fudan University, and has a strong record of HIV research. We will place two integrated hearing testing systems at the center, and provide training in performing the testing. HIV negative, HIV positive individuals not on ART, and HIV positive individuals on a variety of different ART regimens will be enrolled, and studied with a central-auditory-processing-focused protocol. The combination of the hearing testing systems with the research-experienced, high-volume clinic in Shanghai, will provide an excellent environment to confirm and expand knowledge about the central auditory processing deficits in HIV infection, and ascertain whether these findings are related to the duration of infection or particular ART regimens. The information from this study may change how HIV positive are monitored and treated. The new methods developed for detecting central auditory processing deficits, such as the adaptive gap detection algorithm, may be useful for detecting and tracking neurocognitive changes in HIV positive patients.